PRDC11-Jruby-ironruby

(track sponsor)

Jruby &
Iron Ruby

Amir Barylko

Monday, June 13, 2011

AMIR BARYLKO
JRUBY & IRON RUBY

PRAIRIE DEV CON
JUN 2011

Amir Barylko - Jruby & Iron Ruby MavenThought Inc.

WHO AM I?

• Architect

• Developer

• Mentor

• Great cook

• The one who’s entertaining you for the next while!


CONTACT AND MATERIALS
• Contact me: amir@barylko.com, @abarylko

• Blog:http://www.orthocoders.com

• Site:http://www.maventhought.com

• Download: http://www.orthocoders.com/presentations.


RUBY INTRO
Dynamic languages
Toolbox
Features


DYNAMIC LANGUAGES

 High level
 Dynamically typed
 Runtime over compile time
 Closures
 Reﬂection
 Platform independent


DEVELOPERS TOOLBOX
• Make your toolbox grow!

• The right tool for the job

• Not a replacement

• Combine strengths

• Problem solving


WELCOME TO RUBY

 Created in mid-90s by  Several implementations:
“Matz” Matsumoto in Japan MRI, YARB, JRuby
 Smalltalk, Perl inﬂuences  Totally free!!
 Dynamic typing
 Object Oriented
 Automatic memory
management


RUBY FEATURES

 Everything is an expression  Operator overloading,
ﬂexible syntax
 Metaprogramming
 Powerful standard library
 Closures
 Garbage collection
 Exceptions


RUBY SUPPORT

 Hundreds of books  Lots of great web sites:
basecamp, twitter, 43
 User conferences all over things, hulu, scribd,
the world slideshare, Justin.tv
 Active community (you can  Lots of web frameworks
create a conference in your inspired by Ruby on Rails
own city and top Ruby
coders will go there to
teach others, invite them
and see)


RUBY LANGUAGE
Basic Types
Control Structures
Methods
Modiﬁers


BASIC TYPES
 Numbers
1.class => Fixnum
1.1.class => Float
(120**100).class => Bignum
3.times {puts “he “}


BASIC TYPES II
• Strings

'he ' + 'he' => he he
“That's right” => That's right
'He said “hi”' => He said “hi”
“He said “hi”” => He said “hi”
“1 + 1 is #{1+1}” => 1 + 1 is 2
"#{'Ho! '*3}Merry Christmas" =>Ho! Ho! Ho! Merry
Christmas


BASIC TYPES III
 Arrays
a = [1, 5.5, “nice!”]
1 == a.first
1 == a[0]
nil == a[10]
a[1] = 3.14
a.each {|elem| puts elem}
a.sort


BASIC TYPES IV
• Hashes
h = {“one” => 1, 1 => “one”}
h[“one”] == 1
h[1] == “one”
h[“two”] == nil
h.keys == [“one”, 1] (or is it [1, “one”] ?)
h.values == [“one”, 1] (or is it [1, “one”] ?)
h[“one”] = 1.0


BASIC TYPES V
 Symbols: constant names. No need to declare, guaranteed
uniqueness, fast comparison

:apple == :apple
:orange != :banana
[:all, :those, :symbols]
{:ca => “Canada”, :ar => “Argentina”, :es => “Spain”}


CONTROL STRUCTURES
 if
if count < 20
puts “need more”
elsif count < 40
puts “perfect”
else
puts “too many”
end
 while
while count < 100 && need_more
buy(1)
end

CONTROL STRUCTURES II
 Statement modiﬁers
buy while need_more?

buy(5) if need_more?

buy until left == 0

buy unless left < 5


CONTROL STRUCTURES III
• Case
case left
when 0..5
dont_buy_more
when 6..10
buy(1)
when 10..100
buy(5)
end


METHODS
 Simple
def play(movie_path)
....
end

 Default arguments
def play(movie_path, auto_start = true, wrap = false)
....
end


METHODS II
 Return value: the last expression evaluated, no need for
explicit return
def votes(voted, num_votes)
voted && num_votes || nil
end

 No need for parenthesis on call without arguments (same
syntax to call a method and a ﬁeld)
buy() == buy
movie.play() == movie.play


METHODS III
 No need also with arguments (but careful!! only if you know
what you are doing)

movie.play “Pulp fiction”, false, true


RUBY LANGUAGE II
Classes
Mixin
Enumerable


CLASSES & OBJECTS

 Initializer and instance variables
class Movie
def initialize(name)
@name = name
end

def play
puts %Q{Playing “#{@name}”. Enjoy!}
end
end

m = Movie.new(“Pulp fiction”)
m.play

=> Playing “Pulp fiction”. Enjoy!


CLASSES & OBJECTS II
 Attributes
class Movie
def initialize(name)
@name = name
end

}
def name # attr_reader :name
@name
end # attr_accessor :name

def name=(value) # attr_writter :name
@name = value
end

end

m = Movie.new('Brazil').name = “Pulp fiction”


CODE ORGANIZATION
 Code in files with .rb extension
 Require 'movie' will read movie.rb file and make its methods
available to the current file
 Require 'media/movie' will read file from media dir relative
to the current working dir
$LOAD_PATH << 'media'
require 'movie'


CODE ORGANIZATION II
 Relative to this ﬁle:
require File.join(File.dirname(__FILE__), 'media/movie')


MIXINS
 What about module “instance methods”?
 One of the greatest Ruby features!
 You can deﬁne functions in Modules, and get them added to
your classes.
 Great code reuse,
 Multiple inheritance alternative.
 Code organization


ENUMERABLE
 Enumerable mixin, from the standard library documentation:

The Enumerable mixin provides collection
classes with several traversal and
searching methods, and with the ability to
sort. The class must provide a method each,
which yields successive members of the
collection


ENUMERABLE II
 It provides useful methods such as:

 map

 to_a

 take_while

 count

 inject


EXAMPLES
rSpec
Enumerable
Method Missing
Sinatra
BDD Cucumber
DSL


RSPEC TESTING LIBRARY
require 'java'
require 'rubygems'

java_import 'MovieLibrary'
java_import 'Movie'

describe MovieLibrary do

it "should be created empty" do
lib = MovieLibrary.new
lib.contents.should be_empty
end

it "should add an element" do
m = Movie.new 'Blazing Saddles'
lib.add m
lib.contents.should include(m)
lib.contents.count.should == 1
end

end


ENUMERBLE MIXIN
require 'rubygems'
java_import 'Movie'

class MovieLibrary
include Enumerable
def each(&block)
contents.each(&block)
end
end


ENUMERBLE MIXIN

lib.add(Movie.new "Blazing Saddles")
lib.add(Movie.new "Spaceballs")
lib.add(Movie.new "Young Frankenstein")

lib.each { |m| puts "The movie is #{m.title}"}

puts "nn**** Using Inject"
lib.inject([]) { |a, m| a << m.title }
.each { |s| puts "The movie is #{s}" }

puts "nn*** Using find"
lib.find_all { |m| m.title.end_with? 's' }
.each { |m| puts "The movies that end with s: #{m.title}"}


EXTEND LIBRARY
WITH METHOD MISSING
require File.dirname(__FILE__) + "....bin/Debug/MavenThought.MovieLibrary.dll"
require 'rubygems'
include MavenThought::MovieLibrary

class Library
def method_missing(m, *args)
if m.id2name.include?("find_by")
field = m.id2name.sub( /find_by_/, "")
contents.find_all( lambda { |m| m.send(field) == args[0] } )
else
super
end
end
end

lib = Library.new

lib.add Movie.new( "Blazing Saddles", System::DateTime.new(1972, 1, 1))
lib.add Movie.new( "Spaceballs", System::DateTime.new(1987, 1, 1))

puts "Using find by title #{lib.find_by_title( "Blazing Saddles" )}"


SIMPLE WEB WITH SINATRA
require 'rubygems'
require 'sinatra'
require 'haml'
require 'singleton'

java_import 'Movie'

class MovieLibrary
include Singleton
end

# index
get '/' do
@movies = MovieLibrary.instance.contents
haml :index
end

# create
post '/' do
m = Movie.new(params[:title])
MovieLibrary.instance.add m
redirect '/'
end


BDD WITH CUCUMBER
Feature: Addition
In order to make my library grow
As a registered user
I want to add movies to the library

Scenario: Add a movie
Given I have an empty library
When I add the following movies:
| title | release_date |
| Blazing Saddles | Feb 7, 1974 |
| Young Frankenstein | Dec 15, 1974 |
| Spaceballs | Jun 24, 1987 |
Then The library should have 3 movies
And "Blazing Saddles" should be in the list with date "Feb 7, 1974"
And "Young Frankenstein" should be in the list with date "Dec 15, 1974"
And "Spaceballs" should be in the list with release date "Jun 24, 1987"


BDD WITH CUCUMBER
require File.dirname(__FILE__) + "...MavenThought.MovieLibrary.dll"

include MavenThought::MovieLibrary

Given /^I have an empty library$/ do
@lib = Library.new
end

When /^I add the following movies:$/ do |table|
table.hashes.each do |row|
movie = Movie.new row[:title], System::DateTime.parse(...)
@lib.add movie
end
end


DSL I
RAKE
desc "Builds the project"
task :build do

call_target msbuild_cmd, :build
end

desc "Rebuild the application by cleaning and then building"
task :rebuild => [:clean, :build]

desc "Runs all the tests"
task :test => ["test:all"]


DSL II
CRON - WHENEVER
every 10.minutes do
runner "MyModel.some_process"
rake "my:rake:task"
command "/usr/bin/my_great_command"
end

every 2.days, :at => '4:30am' do
command "/usr/bin/my_great_command"
end


QUESTIONS?

(Don’t be shy)


ONLINE RESOURCES
 IronRuby: http://ironruby.net/
 Jruby: http://jruby.org
 Ruby language site: http://www.ruby-lang.org
 rSpec: http://rspec.info/
 Sinatra: http://www.sinatrarb.com/
 Cucumber: http://cukes.info/
 Rake: http://rake.rubyforge.org/

PRDC11-Jruby-ironruby

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